Method and system for obtaining brain characteristic parameters, thrombolysis decision guideline system and method thereof, provide middle of reference data for early diagnosis and treatment of acute ischemic brain death, and provide effective reference data for thrombolytic therapy. The present invention uses diffusion-weighted imaging, comparing to the clinical programs of diffusion-weighted imaging and perfusion weighted imaging, perfusion weighted imaging can omitted and the degree of functional characterization of perfusion abnormalities is reflected without the perfusion weighted imaging, to provide middle data of brain tissue can be saved and the risk of thrombolytic therapy. The present invention based on ADC low signal constraint and DWI high signal constraint DWI binarization processing to obtain the core area and transition area, that is more accurate.